IrfanView - Optimize?

[Terry Pinnell]

Anyone know exactly what the Optimize operation does please? All I can
find in Help is:

"Click on the Options Menu, then JPG Lossless Operations. A dialog
allows you to rotate, flip, optimize or clean a JPG file."

On the few examples (b/w scans) I've tried, I can't *see* any
difference.

And same query for 'Clean'?

 

[Azzman]

Anyone know exactly what the Optimize operation does please? All I can
find in Help is:

"Click on the Options Menu, then JPG Lossless Operations. A dialog
allows you to rotate, flip, optimize or clean a JPG file."

On the few examples (b/w scans) I've tried, I can't *see* any
difference.

And same query for 'Clean'?

For lossless rotation, here's some info:

http://www.impulseadventure.com/photo/lossless-rotation.html

HTH

 

[Mike S.]

Anyone know exactly what the Optimize operation does please?

It probably does what jpegtran does; i.e. "performs optimization of
entropy encoding parameters". AFAIK this means it rearranges the Huffman
tables so that they are more efficient, reducing the file size very
slightly.

The result is at the file/encoding level; i.e. NOT something that you will
be able to detect by looking at the encoded image, which is unchanged.

 

[Terry Pinnell]

It probably does what jpegtran does; i.e. "performs optimization of
entropy encoding parameters". AFAIK this means it rearranges the Huffman
tables so that they are more efficient, reducing the file size very
slightly.

The result is at the file/encoding level; i.e. NOT something that you will
be able to detect by looking at the encoded image, which is unchanged.

Thanks - I'll quietly ignore it then!